Hello everyone!
As my first MYOG project I am going to make synthetic (Climashied APEX 133g/m2) quilt with shock cord and velcro strips at the bottom to form the footbox. I want to mix waterproof and breathable fabric in the top layer and fully breathable bottom layer as shown in the picture (there are commercial quilts that use similar idea). It hope it will help in some situations and the waterproof fabric might be cheaper.

I have some questions:
1. Do you think it is good idea or recommend other solutions?
I need simple design in my first project.
2. Warmth question. How would you rate APEX against 800FP down – how much down would be equivalent in a quilt?
3. What dimensions a,b,c would you use in this (hopefully) 3 season quilt? I am 178cm, slim.
The Nunatak Arc Alpinist has 55in top and 38in bottom, but I am not sure how exactly is it measured (flat?). What about length? This type of quilt bottom closure takes some of its length away.
4. I have never used Climashield APEX – could you confirm that I don't need downproof fabric.
5. Is too much breathability of the top layer bad for the quilt warmth?
In commercial quilts the downproof fabric like M50 or Pertex Quantum is windproof. Is it neccesary to keep warm air inside quilt? I would like to use cheap nylon that is water repellant, but definitely not windproof (you can breathe through it easily) but I am afraid it will ruin properties of the quilt.
6. Somewhere I have seen the hand sewn thread loops that keep insulation in place, but do not compress it. Are they necessary or this (continuous filament) insulation could only be sewn through on the perimeter?
7. Some quilts (Sierra Sniveler etc) have slit in the middle that allows you to wear quilt when necesary. It makes design more complicated, but looks like excellent idea. What do you think about it? How is it closed (velcro?)?
I am especially concerned with question number 5.
Thanks in advance for all your answers and suggestions!

